1. Field of the Invention
The present invention relates a method of providing data services in a terrestrial DMB system, and more particularly to a method of downloading and executing data service data through a terrestrial DMB system. Hereinafter, the term “data service” is used as distinguished from video and audio data service.
2. Description of the Related Art
The terrestrial DMB system is to transmit video services, audio services, and data services. It enables each broadcasting station to transmit an ensemble containing video service, audio service, and data service, each of which services consists of one or more service components. In order to transmit such information, the DMB system is composed of a transmission frame, which is illustrated in FIG. 1.
A conventional DMB transmission frame, with reference to FIG. 1, includes a synchronization channel 11 for transmitting internal information of the DMB transmission system, a fast information channel (FIC) 12 allocated for transmitting information requiring quick access by the DMB receiver, and a main service channel (MSC) 13 for transmitting main services like service components.
More specifically describing each channel, the synchronization channel 11 for transmitting the internal information of the DMB transmission system includes the information of transmission frame synchronization, automatic frequency control, channel state estimation, and transmission identification.
The FIC 12 comprises a plurality of fast information blocks (FIBs) 101-1 to 101-n, containing the multiplex configuration information (MCI) on the structure of the ensemble, the service information (SI) on the services in the ensemble, and other data requiring quick transmission.
The MSC 13 is used for transmitting service components such as video component, audio component and data component. It again consists of a plurality of sub-channels each coded in convolution. The sub-channels consist of a plurality of common interleaved frame (CIFs) 102-1 to 102-n.
The structure and length of the transmission frame varies with transmission mode, but the DMB system adopts the FIBs 101-1 to 101-n and CIFs 102-1 to 102-n in order to provide a transmission mode not affected by the kinds of the data transmitted through the FIC 12 and MSC 13. Namely, the data is transmitted using the FIBs 101-1 to 101-n and CIFs 102-1 to 102-n regardless of the transmission mode. It is only necessary to specify the number of the FIBs 101-1 to 101-n and CIFs 102-1 to 102-n inputted according to the transmission mode. Table 1 shows the number of FIBs and CIFs specified according to the transmission modes of the terrestrial DMB system.
TABLE 1Length ofTransmissionTransmissionNumber of FIBs PerNumber of CIFs PerModeFrameTransmission FrameTransmission FrameI96 ms124II24 ms31III24 ms41IV48 ms62
In addition, Table 2 shows an example of the services planned to be provided by the terrestrial DMB system in the Republic of Korea.
TABLE 2Plan of Channel StructureName ofChannel-Broadcast Type-OperationalCompanyTransmission CapacityMethodField of BroadcastingKBSKBS-Mobile 1-TV-548kDirectVersatile ProgramOperationKBS-Mobile 3-Radio-128kDirectMusicOperationKMMB-R-Radio-128kRent (KMMB)Daily EconomyOZIC-Radio-128kRent (CJMusicMedia)KBS-Mobile 5-Data-220kDirectVersatile ProgramOperationMBCMBC DMB TV-TV-548kDirectVersatile ProgramOperationMBC DMB Radio-Radio-DirectVersatile Program128kOperationMBN Economy Radio-Radio-Rent (MBN)Economy128kARIRANG English Radio-RentKorean CultureRadio-128k(InternationalBroadcastingExchangeFoundation)MBC DMB Data-Data-220kDirectVersatile ProgramOperationSBSSBS DMB TV-TV-544kDirectVersatile ProgramOperationSBS DMB Radio-Radio-128kDirectVersatile ProgramOperationTBS DMB Radio-Radio-128kRent (TBS-TrafficSeoul)KYUNGGI DMB-Radio-Rent (KyunggiCulture and ArtRadio-128kBroadcasting)HANGYEORAI DMB Data-Data-96kRentCareer and Education(HangyeoraiNewspaperLGT DMB Data-Data-96kRent (LGLeisure andTelecom)EntertainmentSBS DMB Data-Data-32kDirectNew Technologies, NewOperationServices,Development/Experiment(Versatile Program)
Describing an ensemble in connection with the MBC in Table 2, the service structure of the ensemble used by the MBC consists of one video service, three audio services, and one data service. Thus, the DMB system features a basic broadcast signal loaded with multiple services such as video, audio and data services.
The data service may be BWS (Broadcast Web Site), EPG (Electronic Program Guide), Slide Show, or Download Java Application, etc. In order to receive a data service, the DMB subscriber may use the data for the data service (hereinafter referred to as “data service data”) loaded in the broadcast signal transmitted through the DMB system. In this case, the DMB system provides only one-way communication services broadcast from the broadcasting station to the DMB receiver. Thus, the DMB receiver cannot distinguish the beginning and ending of a received data service data, or to selectively receive a part of the data service data that has not been received. Hence, this problem is resolved by the broadcasting station repeatedly transmitting the same data with a given period.
The protocols used for transmitting data in the terrestrial DMB system may be generally divided into three different protocols. The first is MOT (Multimedia Object Transfer) protocol, which is most used for transmitting file-type data. This enables a file containing the data and a header or directory containing the information of the file to be transmitted together, so that the DMB receiver can correctly receive the MOT data by using the header or directory. Examples of the data services using the MOT protocol are BWS, EPG, Slide Show, etc. The second is TDC (Transparent Data Channel) protocol, which is most used for transmitting continuous data such as data stream, e.g., TPEG (Transport Protocol Expert Group). And the third is IP (Internet Protocol) tunneling protocol, which is used or transmitting IP data.
When the DMB subscriber selects the data service, the DMB receiving terminal begins to download the data contained in the ensemble broadcast, so that the user must wait until the download is complete before enjoying the service after selection of the data service. Namely, the data service can only be executed after downloading all the data service data, and therefore the subscriber must wait for the time taken for the downloading to complete. For example, if the DMB subscriber selects a BWS service, the subscriber must wait until the DMB receiving terminal has downloaded all the file information included in the selected service. Assuming that the time required for downloading all the data contained in a BWS service be 3 minutes, then the subscriber must wait at least 3 minutes after selection of the service before enjoying the selected service. This is a source of inconvenience for the user which the user may not accept and, hence, reject further use of the service.